System and method for monitoring and maintaining hydrostatic pressure during tripping operations, stripping operations, and axial pipe operations

ABSTRACT

The trip system closely monitors and ensures that the hydrostatic pressure of the wellbore stays consistent throughout the tripping process, stripping process, and axial pipe operations. The core components of the system include, but are not limited to, an advanced automation system that controls a back-pressure device, including but not limited to a choke, a rotary ball valve, or other flow control devices. The automation system also monitors upstream and downstream flow measurement components. The trip system also provides a pump system to circulate drilling fluid from the trip tank across the top of the wellhead and/or at a lower portion below the RCD.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a continuation of U.S. PatentApplication No. 62/778,182 entitled SYSTEM AND METHOD FOR MONITORING ANDMAINTAINING HYDROSTATIC PRESSURE DURING TRIPPING OPERATIONS, STRIPPINGOPERATIONS, AND AXIAL PIPE OPERATIONS filed on Dec. 11, 2018 that ishereby incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not Applicable.

RESERVATION OF RIGHTS

A portion of the disclosure of this patent document contains materialwhich is subject to intellectual property rights such as but not limitedto copyright, trademark, and/or trade dress protection. The owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure as it appears in the Patent and TrademarkOffice patent files or records but otherwise reserves all rightswhatsoever.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention is related to a tripping system in a drillingoperation. More specifically, the present invention is related to atripping system for maintaining wellhead pressure. The present inventionmonitors the upstream and downstream flow measurements of drilling fluidthrough the wellhead. The present invention provides a back pressuredevice for maintaining wellhead pressure to alleviate pressuredeviations. The present invention also prescribes the rate of movementof the pipe within the well.

A pipe trip, also known as tripping pipe, is the act of pulling thedrill string out of the hole or replacing it in the hole. This is acommon operation used in the drilling practice for many differentreasons such as:

-   -   Damaged or worn out drill bit;    -   Modification to Bottom Hole Assembly (BHA);    -   Drilling operation has been completed;    -   To clean up the sides of open hole (Wiper Trip); and    -   Running casing.

The act of replacing drill string into the wellbore when the blowoutpreventers (BOPS) are closed and pressure is contained in the well is aprocedure known as stripping pipe. This procedure is required when thehydrostatic overbalance pressure of the wellbore has been compromisedand an influx has been detected.

Both tripping and stripping pipe rely heavily on monitoring thehydrostatic pressure of the wellbore. This hydrostatic pressure isdetermined by the weight of the drilling fluid column and total verticaldepth of the wellbore. Before the tripping process can take place, thecorrect weight of the drilling fluid must be determined and circulatedthroughout the wellbore to prevent an influx or fracture of the well.During circulation of the desired weight drilling fluid, the remainingcuttings from the drilling process will be carried out of the well andprocessed by the mud cleaning system. Once the well bore has beenconditioned, the rig will then align the flow path to the trip tank. Toensure there is not a drop in hydrostatic pressure during the trippingprocess, each piece of drill pipe that is pulled from or placed back inthe wellbore is counted. Calculations are performed to determine howeach piece of drill pipe will affect the fluid volume of the wellbore.This process is generally assigned to someone that will verify thevolume of the trip tank has changed the correct amount per each sectionof pipe pulled wet or dry.

Surge and Swab are other issues that can arise while pulling pipe out orrunning pipe and casing back in the well bore. The movement of the drillstring when pulling pipe out of the well bore can cause the pressurecreated by the drilling fluid on the bottom of the hole to decrease.This decrease in pressure is caused by friction between the movement ofthe drill pipe and the stationary drilling mud. This effect is known asswabbing and poses the risk of allowing an influx to enter the wellbore. The reverse of swabbing is surging. While running drill pipe orcasing into the well bore, the bottom hole pressure can increase,causing a possible fracture in the formation.

Over the past 15 years, tripping has contributed to multiple wellcontrol incidents, all of which have the possibility for lost drillingfluids to the environment, injury to personnel, and potential death topersonnel. According to a study completed by Bourgoyne Engineering LLCand a team from LSU in July 2017, the total number of recorded wellcontrol incidents caused by tripping since 2006 in the U.S. was over 30.(Bourgoyne Engineering LLC, 2017).

The present invention provides a system to monitor and reduce wellcontrol incidents and decrease the frequency of safety and environmentalincidents attributed to the tripping process. The present inventionoptimizes the integration of the system with various rig configurationsused in the industry today.

SUMMARY OF THE INVENTION

The advanced automated system of the present invention enables thesystem to closely monitor and maintain the consistency of thehydrostatic pressure of the wellbore throughout the tripping process.The core components of the system include, but are not limited to, anadvanced automation system that controls a back-pressure device,including but not limited to a choke, a rotary ball valve, or other flowcontrol devices. The automation system also monitors upstream anddownstream flow measurement components. The automation system alsomonitors the wellhead pressure via a wellhead pressure monitor. Thepresent invention also provides a pump system, such as a mud pump orother pump system, to circulate drilling fluid from the trip tank acrossthe top of the wellhead.

The automation system of the present invention monitors systemcomponents and rapidly notifies any abnormalities in trip tank orwellhead parameters. Other features of the system include mitigatingeffects of surge and swab by applying required pressures to the well andproviding the optimal speed to move the drill pipe or casing.

It is an object of the present invention to provide an automated tripsystem.

It is also an object of the present invention to reduce well controlincidents.

It is also an object of the present invention to decrease the frequencyof safety and environmental incidents attributed to the tripping orstripping process.

It is also an object of the present invention to decrease the number ofsafety and environmental incidents attributed to the tripping orstripping process.

It is also an object of the present invention to monitor the hydrostaticpressure of the wellbore.

It is also an object of the present invention to maintain theconsistency of the hydrostatic pressure of the wellbore during thetripping process, stripping process, and axial pipe operations.

It is also an object of the present invention to control a back pressuredevice.

It is also an object of the present invention to monitor upstream anddownstream flow.

It is also an object of the present invention to circulate drillingfluid from the trip tank across the top of the wellhead.

It is also an object of the present invention to notify the user of anyabnormalities in trip tank parameters.

It is also an object of the present invention to mitigate effects ofsurge and swab.

It is also an object of the present invention to apply pressure to thewellhead.

It is also an object of the present invention to provide the optimalspeed to move the drill pipe and/or casing.

It is also an object of the present invention to protect rig personneland the environment.

In addition to the features and advantages of the present invention,further advantages thereof will be apparent from the followingdescription in conjunction with the appended drawings.

These and other objects of the invention will become more fully apparentas the description proceeds in the following specification and theattached drawings. These and other objects and advantages of the presentinvention, along with features of novelty appurtenant thereto, willappear or become apparent in the course of the following descriptivesections.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following drawings, which form a part of the specification andwhich are to be construed in conjunction therewith, and in which likereference numerals have been employed throughout wherever possible toindicate like parts in the various views:

FIG. 1 is a schematic view of one embodiment of the present invention;

FIG. 2 is a schematic view of one embodiment of the present invention;

FIG. 3 is a flowchart showing a process of one embodiment of the presentinvention;

FIG. 4 is a flowchart showing a process of one embodiment of the presentinvention; and

FIG. 5 is a flowchart showing a process of one embodiment of the presentinvention.

DETAILED DESCRIPTION

The present invention provides an automated trip system generally shownas 100. The automated trip system 100 controls back pressure device 102.The automated trip system 100 also monitors upstream flow component atpump 108, downstream flow component 106, trip tank monitor 119, fluidcontainment system monitor 127, and wellhead pressure monitor 130.

The trip system 100 also provides a pump system 108, such as a mud pumpor other pumping system. The pump system 108 circulates drilling fluidfrom the trip tank through the well as shown in FIGS. 1 and 2. The pumpsystem 108 circulates drilling fluid from the trip tank 118 into thewell. In one embodiment, the pump system 108 circulates drilling fluidinto the well at the RCD 110 or into a lower portion of the well atspool 112, or into the BOP 124. In one embodiment, the pump system 108circulates drilling fluid into the blowout preventer (BOP) 124 as shownat spool 112. The pump system 108 may alternatively circulate thedrilling fluid towards a lower portion of the wellhead.

Tripping pipe, stripping pipe, and other axial pipe operations rely onmonitoring the hydrostatic pressure of the wellbore. The hydrostaticpressure is determined by the weight of the drilling fluid column andtotal vertical depth of the wellbore. The trip system 100 monitors thehydrostatic pressure of the well to determine well conditions andapplies pressure to the well. The trip system of the present inventionalso determines the optimal speed to move the drill pipe and/or casingwithin the well.

The trip system 100 monitors the trip tank 118 to determine the rate atwhich the fluid enters and leaves the well. The trip system 100 monitorsthe trip tank 118 and the active fluid system 126. The trip system 100detects deviations in the fluid flow to detect and mitigate thedeviations more quickly by monitoring the trip tank 118. The trip tank118 has a much smaller volume than the active fluid system 126. The tripsystem 100 detects the deviations more quickly by monitoring the statusof the trip tank 118 due to the smaller volume of the trip tank 118.

FIGS. 1 and 2 show different flow diagrams of the present invention forcirculation of fluid across the well at two different locations for wellcontrol. The circulation of the drilling fluid across the well assistswith maintaining the hydrostatic pressure of the well under differentconditions. The trip system enables circulation of the drilling fluidthrough an upper portion of the wellhead, such as the RCD 100, orthrough a lower portion of the wellhead, such as spool 112. FIG. 1 showsthe flow of the drilling fluid through the trip system 100 at an upperportion of the wellhead, such as RCD 110, to adjust pressure within thewell. FIG. 2 shows the flow of the drilling fluid through the tripsystem 100 into the BOP 124 at spool 112 to adjust pressure within thewell. In one embodiment, the spool 112 may be located below the piperams. In other embodiments, the spool 112 may be located at any pointbelow the RCD for circulation of the drilling fluid below the RCD.

The trip system 100 utilizes a trip tank 118 storing at least some ofthe drilling fluid. The trip tank 118 provides drilling fluid to thetrip system. The trip tank 118 also receives drilling fluid from thetrip system.

Pump 108 directs the drilling fluid into the well and out of the well.Pump 108 controls the upstream flow of the drilling fluid into the wellduring the tripping process. The trip system 100 monitors the rate atwhich the pump 108 is pumping the drilling fluid into the well. The rateat which the pump 108 pumps the drilling fluid into the well from thetrip tank 118 provides the trip system 100 with the upstream flowmeasurement needed for operation of the system 100.

The trip system 100 receives the downstream flow measurement from thedownstream flow measurement device 106. The downstream flow measurementdevice 106 is positioned downstream from the well to measure the flow ofthe drilling fluid from the well.

The trip system 100 uses the information received from the pump 108 andthe downstream flow measurement device 106 to calculate the measurementsneeded for automation of the system 100. The data received from the pump108 and the downstream flow measurement device 106 are applied to thecalculations for advising operation of the back pressure device 102 orotherwise adjusting the back pressure device 102. These calculations cancause the system 100 to open or close the back pressure device 102 tomaintain the pressure within the well or to alleviate pressuredeviations in bottom hole pressure.

The system quickly determines potential situations regarding thehydrostatic pressure of the well by monitoring the downstream flow andthe upstream flow. The trip system 100 monitors deviations in thecirculation of the drilling fluid of the well. For definition withinthis application, positive deviation will indicate a greater downstreamflow measurement than the upstream flow measurement. Negative deviationwill indicate a greater upstream flow measurement than the downstreamflow measurement. The trip system 100 also monitors potential issues ofsurging and swabbing.

A negative deviation of the fluid flow indicates the loss of drillingfluid. Such a loss alerts the user to a potential fracture in the well.A positive deviation of the fluid flow indicates a gain of fluid intothe system. Such a gain in fluid flow alerts to a potential influx inthe well.

The system also provides secondary devices to determine deviations inthe fluid flow. The system provides a trip tank monitor 119 to determinethe amount of fluid within the trip tank 118. If a positive deviation inthe fluid flow occurs, the amount of fluid within the trip tank 118 willincrease. If a negative deviation in the fluid flow occurs, the amountof fluid within the trip tank 118 will decrease. In one embodiment, thesystem establishes a lower volume limit and an upper volume limit. Thesystem detects a negative deviation if the volume of the drilling fluidwithin the trip tank is below the lower volume limit. The system detectsa positive deviation if the volume of the drilling fluid within the triptank is above the upper volume limit. In one embodiment, the systemadjusts the upper volume limit and the lower volume limit based upon theamount of pipe downhole as discussed below.

FIGS. 1 and 2 show the different variations for circulating fluidthrough the well to reduce deviations in bottom hole pressure. FIG. 1shows circulation of the fluid within the well at the RCD 110. FIG. 2shows circulation of the fluid within the well at the spool 112.

Referring to FIG. 1, the trip system 100 adjusts the pressure at theback pressure device 102. Pump 108 directs drilling fluid from the triptank 118 into the RCD 110 at inlet 114. Drilling fluid flows from theRCD 110 through outlet 116. The drilling fluid flows to a back pressuredevice 102 after exiting outlet 116. Such a back pressure device 102 mayinclude, but is not limited to, a choke, a rotary ball valve, or otherflow control devices.

The drilling fluid flows from the back pressure device to the downstreamflow measurement device 106. The flow of the drilling fluid is thenmeasured at the downstream flow measurement device 106. The downstreamflow measurement device 106 may be positioned in front of the backpressure device 102 if the downstream flow measurement device 106 israted for the appropriate pressure.

The drilling fluid flows from the downstream flow measurement device 106into the trip tank 118. The drilling fluid can then be recirculatedthrough the well from the trip tank 118.

The trip system 100 shown in FIG. 2 applies the pressure below the RCDwithin the BOP 124. The trip system 100 monitors the upstream anddownstream flow measurements via the pump 108 and the downstream flowmeasurement device 106 as described above. The pump 108 applies thedrilling fluid from the trip tank to the inlet 120 of spool 112. Thepump 108 circulates the fluid across a portion of the wellhead below theRCD 110. The downstream measurement device 106 determines the downstreamflow measurement by measuring the rate at which the drilling fluid exitsspool 112 via outlet 122. The drilling fluid flows from the spool 112 tothe back pressure device 102 through the downstream flow measurementdevice 106 to the trip tank 118.

FIGS. 1 and 2 show the drilling fluid being circulated through differentareas of the wellhead. One embodiment of the invention provides forcirculation of the drilling fluid at the RCD 110 as shown in FIG. 1, tothe spool 112 within the BOP 124 shown in FIG. 2, or to both the RCD 110and the spool 112 as shown in FIGS. 1 and 2.

To maintain the pressure, the trip system adjusts the back pressuredevice 102. The trip system 100 reduces or otherwise closes the backpressure device 102 to maintain the pressure in instances in which thewell is losing pressure. The trip system 100 opens or otherwiseincreases the opening of the back pressure device 102 to maintainpressure in instances in which the well pressure is increasing. The backpressure device 102 adjusts accordingly to maintain the pressure throughthe circulation of the drilling fluid through the wellhead at the RCD110, the spool 112, or both the RCD 110 and the spool 112.

The trip system 100 alerts the user to deviations in the fluid flow.Such deviations in the fluid flow indicate that an issue with the wellis occurring. Such issues include, but are not limited to, surging,swabbing, influx, and/or fracture.

The back pressure device 102 opens and closes to maintain thehydrostatic pressure of the wellhead. The trip system 100 monitors theupstream flow of the drilling fluid and the downstream flow of thedrilling fluid to determine deviations in the hydrostatic pressure. Thetrip system 100 then adjusts the back pressure device 102 depending onthe deviations determined at the pump 108 and the downstream flowmeasurement device 106.

To provide additional information, the trip system 100 utilizes awellhead pressure monitor 130. The wellhead pressure monitor 130combined with the deviations in fluid flow provide sufficientinformation to the user in a timely manner to allow the user to beproactive in mitigating the issue. The situation may require closing thewell, manipulation of the back pressure device 102, or other actionsthat may be necessary for continued operation of the well.

FIGS. 3 and 4 show the operation of the tripping system. The trippingsystem monitors the operating conditions of the trip tank at MonitorStep 132. Such monitoring involves monitoring the flow rate of thedrilling fluid from the trip tank to the annulus (the upstreammonitoring), the flow rate of the drilling fluid from the annulus to thetrip tank (the downstream monitoring), and/or the volume of the drillingfluid within the trip tank. The system identifies the positive flowdeviation of the flow as shown in FIG. 3 and the negative flow deviationas shown in FIG. 4.

To identify the flow deviation, the system provides two differentmonitoring systems. These alternative systems provide for redundancy inmonitoring the operation of the trip tank. The system monitors the triptank conditions by identifying changes in flow rates and/or monitoringthe volume of the drilling fluid within the trip tank.

The system monitors the flow rates of the drilling fluid to and from thetrip tank. The system compares the upstream flow measurement to thedownstream flow measurement. As indicated above, positive deviationindicates a greater downstream flow measurement than the upstream flowmeasurement. Negative deviation indicates a greater upstream flowmeasurement than the downstream flow measurement

The system may also monitor the volume of the trip tank. The volume ofthe trip tank may vary according to the operation of the well. Positivedeviation indicates increased volume of the drilling fluid within thetrip tank. Negative deviation indicates decreased volume of the drillingfluid within the trip tank. In one embodiment, the tripping systemaccounts for the amount of pipe downhole as will be discussed below.

The system monitors the operation of the trip tank via at least one ofthe flow rate comparison or the volume of the drilling fluid within thetrip tank. In one embodiment, the tripping system monitors both the flowmeasurement and the volume of the drilling fluid within the trip tank toprovide for redundancy. A computing device and/or system of oneembodiment monitors the operating conditions of the trip tank. In oneembodiment, the computing device and/or system causes an alarm or otheralert to be activated upon detection of positive deviation and/ornegative deviation. Such an alert may be an audible alarm, emails, textmessages, or other messaging system that alerts the operators.

FIG. 3 shows the operation of the tripping system during detection ofpositive deviation at Positive Deviation Detected Step 134. The systemhas identified that the downstream flow measurement is greater than theupstream flow measurement and/or the volume of the drilling fluid isgreater than the upper volume limit.

Upon detecting positive deviation at the trip tank, the systemidentifies that the hydrostatic pressure should be increased at IncreaseHydrostatic Pressure Step 136. The system then reduces flow of thedrilling fluid through the Back Pressure device at Reduce Flow Step 138.The system may automatically reduce the flow rate through the backpressure device or alert an operator to reduce the flow rate through theback pressure device. Such reduction of the flow rate through the backpressure device may be accomplished by closing the back pressure deviceor otherwise reducing the flow through the back pressure device.

FIG. 4 shows the operation of the tripping system during detection ofnegative deviation at Negative Deviation Detected Step 140. The systemhas identified that the upstream flow measurement is greater than thedownstream flow measurement and/or the volume of the drilling fluid isless than the lower volume limit.

Upon detecting negative deviation at the trip tank, the systemidentifies that the hydrostatic pressure should be decreased at DecreaseHydrostatic Pressure Step 142. The system then increases flow of thedrilling fluid through the Back Pressure device and/or decreases thepump rate at Increase Flow Through Back Pressure Device/Decrease PumpRate Step 138. The system may automatically adjust the back pressuredevice and/or pump to decrease the hydrostatic pressure or alert anoperator to adjust the back pressure device and/or pump. Such increaseof the flow rate through the back pressure device may be accomplished byopening the back pressure device or otherwise increasing the flowthrough the back pressure device.

By monitoring the volume of the drilling fluid within the trip tank, thesystem identifies potential issues earlier than previously available.The amount of pipe used downhole affects the volume of drilling fluidwithin the trip tank. The system must adjust the trip tank limitsaccording to the amount of pipe used downhole. As more pipe is useddownhole, the pipe will occupy space previously occupied by the drillingfluid. Therefore, more drilling fluid will be within the trip tank whenmore pipe is used downhole. Likewise less drilling fluid will be in thetrip tank when less pipe is used downhole. The system calculates thevolume occupied by the pipe used downhole to determine the lower volumelimit and the upper volume limit of the amount of drilling fluid withinthe trip tank.

The amount of drilling fluid within the trip tank should increase as theamount of pipe downhole increases. Likewise, the amount of drillingfluid within the trip tank should decrease as the amount of pipedownhole decreases. The system varies the limits according to thecalculations of the volume of the downhole pipe. As more pipe isdownhole, the system increases the lower volume limit and the uppervolume limit. As less pipe is downhole, the system decreases the lowervolume limit and the upper volume limit.

The amount of pipe downhole may increase or decrease as shown at VaryAmount of Pipe Downhole Step 146. The system via computing device and/orcomputing system of one embodiment, determines the expected change inthe volume of the drilling fluid within the trip tank. The systemdetermines the change at Determine Change Step 148. The system, viacomputing device and/or computing system, adjusts the trip tank limitsidentifying the expected volume of the drilling fluid within the triptank required to identify a positive deviation and a negative deviation(the lower volume limit and the upper volume limit).

The system adjusts the lower volume limit and the upper volume limitaccording to the pipe downhole. The system increases the lower volumelimit and the upper volume limit as more pipe is downhole. In oneembodiment, the system increases the lower volume limit and the uppervolume limit by the change in the amount of volume occupied by the pipedownhole. The system decreases the lower volume limit and the uppervolume limit as less pipe is downhole. In one embodiment, the systemdecreases the lower volume limit and the upper volume limit by thechange in the amount of volume occupied by the pipe downhole.

The system then monitors the volume of the drilling fluid within thetrip tank according to the adjusted trip tank limits at Monitor TripTank Step 152. The system updates the trip tank limits as the amount ofpipe varies.

The tripping system identifies potential issues of the well and takesaction to potentially avoid and/or minimize the effects of such issues.By monitoring the trip tank, the system identifies potential issues atan earlier stage. Such earlier detection allows drilling personnel orthe system to address the issues at an earlier time to potentially avoidand/or minimize the effects of such issues.

From the foregoing, it will be seen that the present invention is onewell adapted to obtain all the ends and objects herein set forth,together with other advantages which are inherent to the structure.

It will be understood that certain features and subcombinations are ofutility and may be employed without reference to other features andsubcombinations. This is contemplated by and is within the scope of theclaims.

As many possible embodiments may be made of the invention withoutdeparting from the scope thereof, it is to be understood that all matterherein set forth or shown in the accompanying drawings is to beinterpreted as illustrative and not in a limiting sense.

What is claimed is:
 1. A tripping system for maintaining pressure in anannulus during axial movement of drilling pipe in a well, the systemcomprising: a trip tank wherein drilling fluid flows from the annulus tothe trip tank, wherein the drilling fluid flows from the trip tank tothe annulus; an upstream flow measurement device that measures flow ofthe drilling fluid from the trip tank to the annulus; a downstream flowmeasurement device that measures flow of the drilling fluid from theannulus to the trip tank; a pump that directs drilling fluid to theannulus; a back pressure device located downstream from the annulus,wherein the back pressure device opens and closes to vary the flow ofthe drilling fluid from the annulus to adjust the back pressure of thewell; and wherein the pump circulates the drilling fluid through a spoollocated below a rotating control device connected to the well.
 2. Atripping system for maintaining pressure in an annulus during axialmovement of drilling pipe in a well, the system comprising: a trip tankwherein drilling fluid flows from the annulus to the trip tank, whereinthe drilling fluid flows from the trip tank to the annulus; a volumemeasurement device measuring the volume of the drilling fluid within thetrip tank; a pump that directs drilling fluid from the trip tank to theannulus; a back pressure device located downstream from the annulus,wherein the back pressure device opens and closes to vary the flow ofthe drilling fluid from the annulus to adjust the back pressure of thewell; and a computing device that detects that the volume of thedrilling fluid within the trip tank is not within a lower volume limitand an upper volume limit, wherein the computing device adjusts thelower volume limit and the upper volume based upon the amount of pipewithin the well.
 3. A tripping system for maintaining pressure in anannulus during axial movement of drilling pipe in a well, the systemcomprising: a trip tank wherein drilling fluid flows from the annulus tothe trip tank, wherein the drilling fluid flows from the trip tank tothe annulus; a volume measurement device measuring the volume of thedrilling fluid within the trip tank; a pump that directs drilling fluidfrom the trip tank to the annulus; wherein the pump circulates thedrilling fluid through a spool located below a rotating control deviceconnected to the well.
 4. A tripping system for maintaining pressure inan annulus during axial movement of drilling pipe in a well, the systemcomprising: a trip tank wherein drilling fluid flows from the annulus tothe trip tank, wherein the drilling fluid flows from the trip tank tothe annulus; an upstream flow measurement device that measures flow ofthe drilling fluid from the trip tank to the annulus; a downstream flowmeasurement device that measures flow of the drilling fluid from theannulus to the trip tank; a volume measurement device measuring thevolume of the drilling fluid within the trip tank; a pump that directsdrilling fluid from the trip tank to the annulus, wherein the pumpcirculates the drilling fluid through a rotating control deviceconnected to the well; wherein the pump circulates the drilling fluidthrough a spool located below the rotating control device connected tothe well.